To convert epoch seconds (the number of seconds since January 1, 1970) to the current time on a Linux or UNIX system, you can use the date command.
For example, to convert the epoch seconds 1623490000 to the current time, you can use the following command:
date -d @1623490000
This will output the current date and time in the following format:
Fri Mar 18 14:50:00 UTC 2022
You can also use the -u option to output the date and time in Universal Time (UTC) rather than the local time:
date -u -d @1623490000
You can use the -R option to output the date and time in the HTTP-compatible RFC 2822 format:
date -R -d @1623490000
This will output the date and time in the following format:
Fri, 18 Mar 2022 14:50:00 +0000
You can use the -I option to output the date and time in the ISO 8601 format:
date -I -d @1623490000
This will output the date and time in the following format:
2022-03-18T14:50:00+00:00
You can use the --rfc-3339=seconds option to output the date.